fix file() flags error-check

[divinity76]

the old flag check was flawed and would miss some invalid flags, for example:

file(__FILE__, FILE_APPEND);

is invalid, but the old flags error check would miss it: https://3v4l.org/b2W9u

the new check is also about 7% faster: https://quick-bench.com/q/j3k_unXcE91gVdTRH9Dm0nxpDUA

[divinity76]

i think the ASAN_DEBUG_NTS test just randomly failed for completely unrelated reasons. anyone know how to re-run it? can't find a "re-run test" button 🤔

[nielsdos]

i think the ASAN_DEBUG_NTS test just randomly failed for completely unrelated reasons. anyone know how to re-run it? can't find a "re-run test" button thinking

Only maintainers can re-run it. But it's fine, it's a known flaky test.

[iluuu1994]

Thank you! This change makes sense to me. We'll need to document accordingly (in UPGRADING).

[staabm]

Just fyi: I borrowed the idea and implemented a check in PHPStan, so we can detect similar errors even on older PHP versions

phpstan/phpstan-src#2476

[divinity76]

@iluuu1994 added note in UPGRADING (and that caused a merge conflict, but fixed it)

[iluuu1994]

Thanks! Let's wait for Jakubs review since he's code owner.

[iluuu1994]

Thanks @divinity76!